The present invention concerns the preparation of shields in a physical vapor deposition chamber in order to increase shield adhesion and thereby achieve particle reduction.
In physical vapor deposition (PVD) processes a target material, for example titanium Tungsten, is bombarded by gaseous ions, for example Argon ions. Material from the target is dislodged and sputters onto a work piece. The work piece is generally a semiconductor wafer, but may be, for example, a magnetic disk or a flat panel display.
A PVD chamber generally includes shields in the area immediately around a wafer. The shields prevent excess material sputting from the target from contaminating the remainder of the PVD chamber.
For many types of sputtered materials, the build-up of excess material on the shields eventually results in flaking. At this point it is usually necessary to service the PVD chamber by replacing the shield. If shield replacement needs to be done at approximately the same time as target replacement, the service to shield may be performed without loss of operation time. However, if the shield needs to be replaced much more often than the target this can result in extra down-time of a system which can seriously impair production throughput. It is desirable, therefore, to seek ways to reduce flaking and thereby lengthen the time between shield replacement.